The present invention relates to a hybrid welding apparatus combining arc welding and laser welding, and more specifically, to a hybrid welding apparatus designed so that a tolerance for the angle of a welding head to a bevel of a base metal is wide, energy can be concentrated within a narrower range to deepen the penetration of the base metal, the welding speed is high, and the welding head is small-sized.
Laser welding and gas-shielded arc welding are examples of welding techniques for bonding solid-state metals. In laser welding, laser beam is converged at one point on a welding base metal by means of an optical system composed of lenses and the like. This method is suited for the welding of refractory materials. A dedicated laser welding head is used for the laser welding.
On in other hand, the gas-shielded arc welding, an electric arc is generated between a base metal and a wirelike consumable metal electrode that is fed automatically from a bobbin, and a gas, such as carbonic acid gas, flows out from around the arc to shield weld zones. A dedicated arc welding head is used for the gas-shielded arc welding.
According to the aforesaid laser welding, however, the laser beam is condensed by means of the optical system or lenses, so that an allowance for the angle of the laser beam to the bevel is narrow. Accordingly, the accuracy of the beam angle to the bevel must be maintained exactly. According to the gas-shielded arc welding, moreover, the arc becomes unstable if the welding speed is increased. For stable gas-shielded arc welding, therefore, the feeding speed for the consumable metal electrode is restricted to about 2 m/min.
Hybrid welding, which combines the laser welding and the gas-shielded arc welding, has been employed in an attempt to cover up the drawbacks of the two conventional welding methods.
In hybrid welding, an arc from an electrode and a laser beam are aligned so that their heat energy can be used to weld a weld zone of a base metal. Specifically, a laser welding head and a gas-shielded arc welding head must be inclined at their respective angles to the base metal lest they interfere with each other, in order to align a spot of the laser beam from the laser welding head and a spot of the arc from the arc welding head with the weld zone of the base metal.
Since the heads are inclined with respect to the base metal in this case, however, heat energy losses prevent weld penetration at the base metal from being deep enough.
Since the welding heads are large-sized, there are restrictions on the type of the object which can be welded, as well as the weld zones. The results in unsatisfactory working efficiency. Further, the large-sized welding heads are awkward to handle.